[Jed]: Sulforaphane is a small molecule that was discovered in broccoli by Paul Talalay
and Yuesheng Zhang, his student at the time, in 1992 or so.
They published on it.
And it was of interest in particular because it was a huge inducer of protective enzymes
in people.
Of course, it was known that this occurred in people at the time, but in cell cultures
and in animals, they showed that it up-regulated the protective enzymes, cytoprotective enzyme
system known by some as the phase II enzyme system.
And, Paul then, who was one of the grandfathers of chemo-protection and has...it really helped
make people stand up and pay attention to the fact that you could potentially prevent
diseases like cancer.
Paul asked me to join the group in 1993, and the challenge was, can you get broccoli with
more sulforaphane?
I came from a background in plant bio-technology, and, of course, I said, "Yes, we should be
able to."
And we started trying to breed and cross broccolis to get higher levels of sulforaphane.
Quickly, it became obvious that it was very difficult to predict how much sulforaphane
a broccoli plant would have based on things like smell, touch, color and you pretty much
had to run it through an HPLC to measure levels of sulforaphane.
What's more is we realized that sulforaphane is not what's present in the intact plant.
So what's present in the plant is something called glucoraphanin and that is a thio-glucose
conjugated molecule, not to get too heavily into the biochemistry of it, but it's a bigger
molecule, it's a precursor and it's very stable.
Sulforaphane is not at all stable.
It's highly reactive.
And so at any rate, it turned out that the intact broccoli plants had glucoraphanin at
various levels ranged all over the map, couldn't figure out exactly how much one had without
doing chemical analyses.
And we were going out to the field in the eastern shore of Maryland.
And eventually, winter came along, and we couldn't go out to the fields and get broccoli
anymore.
So we started growing them in incubators in the labs starting from seeds.
And lo and behold, it turns out that broccoli sprouts had much higher levels of the precursor
of sulforaphane, glucoraphanin, than did the mature plants, the heads of broccoli that
you buy in the market.
So we then determined that if you grow broccoli sprouts all the same way, which you pretty
much do if you are a home sprouter or a commercial sprouter, you add a certain amount of light,
you add fresh water, you grow them for a certain amount of time at a certain temperature.
So if you did that with a whole slew of different cultivars, that's the different sub-varieties
of broccoli, you got a range of different activities, different amounts of glucoraphanin.
Anyway, bottom line is by selecting the appropriate genotypes, the appropriate broccoli genetics,
if you will, we identified some varieties that had very high levels of glucoraphanin.
Paul and I made a conscious decision at that time that we were going to promote the use
of broccoli sprouts.
not broccoli seeds.
Because it turns out the seeds had the highest amount on a per gram basis of glucoraphanin.
But at the time, no one had eaten broccoli seeds.
You know, they weren't green.
They didn't have the sort of cachet or the appearance of eating healthy green vegetables.
So we focused on sprouts, which had much higher levels than the mature plants, although lower
levels than the seeds.
And it turns out that then there is an enzyme that the plant tissue contains called myrosinase.
And that enzyme converts glucoraphanin, the precursor, which is stored in vacuoles in
the plant cells to sulforaphane.
And typically in nature, the plant does that as a protective mechanism.
If an insect starts chewing on the leaf of a broccoli plant, for example, it breaks open
cells, right?
And so those cells then release their glucoraphanin and the enzyme that's present at the same
site hydrolyzes glucoraphanin and forms sulforaphane.
And sulforaphane repels those bugs or is in some cases toxic to those bugs.
So they go...and they fly away or they crawl away.
But it turns out that sulforaphane is also a foreign compound for our cells.
But in the process of being recognized and chucked out of the cell, if you will, it up-regulates
the protective enzymes in those cells.
And so that's why it's so special.
[Rhonda]: Like a hormetic effect, like a hormetic effect where...
[Jed]: Yeah.
So clearly, if all you ate was sulforaphane, you'd be in trouble.
[Rhonda]: Yeah.
[Jed]: But the same with just about anything you can suggest.
So it gears up or cranks up the protective mechanisms of the cells.